DESCRIPTION: This application expands upon an ongoing study (R01AA11873) to examine the onset and development of alcohol abuse in 500 adolescents previously diagnosed with Attention Deficit Hyperactivity Disorder ADHD). The proposed study requests a modest amount of additional funding to add measures of licit and illicit drug use and abuse (self-report, parent report, biological assessment) and assessment of additional drug-relevant domains such as subdiagnostic symptoms of abuse, family history of drug abuse, and expectancies for drug effects. Participants will be 500 adolescents, 74 percent of whom had comorbid oppositional defiant (44 percent) or conduct (30 percent) disorder, who were previously diagnosed with ADHD at the Western Psychiatric Institute and Clinic Summer Treatment Program for ADHD. These adolescents, who will be interviewed annually for four years, will range in age from 12 to 26 at initial follow-up contact, representing a wide range of developmental stages that represent different levels of risk for the development of drug abuse. This cohort-sequential design will permit us to evaluate drug use, abuse, and its emergence over time in ADHD children across three developmental periods. The proposed study will also enable comparison of ADHD adolescents' drug use to 200 non-ADHD demographically similar comparison adolescents who will be followed for the same time period. This data set will be unique in several ways, allowing the investigators to address questions regarding ADHD risk for drug use and abuse with much greater scope and precision than previous investigations. Unique advantages of this study include: (1) the sample size will be four times that of the largest existing follow-up study, affording subgrouping on the ADHD sample on key risk factors (e.g., conduct disorder, academic functioning, parental drug and alcohol use), (2) the wide age range of our sample compared to previous studies will yield information both on development of drug use (younger adolescents), as well as on routine drug use and abuse (older subjects) in the same study; (3) drug use and abuse assessment will be far more comprehensive than in previous studies, (4) the clinic-referred sample has a wealth of standardized, objective information on the children and their family functioning at initial contact during childhood not available in previous studies, affording differentiation between childhood and adolescent functioning in our models; and (5) assessment will include comprehensive evaluation of a number of domains in the probands and their families that may explain or escalate ADHD children's risk for later drug abuse.